

class Compiler {
  constructor(vm) {
    this.el = vm.$el;
    this.vm = vm;
    this.compile(this.el);
  }
  compile(el) {
    Array.from(el.childNodes).forEach(node => {
      if (this.isTextNode(node)) {
        this.compileText(node)
      } else if (this.isElementNode(node)) {
        this.compileElement(node);
      }
      if (node.childNodes && node.childNodes.length > 0) {
        this.compile(node)
      }
    })
  }
  compileElement(node) {
    Array.from(node.attributes).forEach(attr => {
      let attrName = attr.name;
      if (this.isDirective(attrName)) {
        attrName = attrName.substr(2)
        let key = attr.value;
        this.update(node, key, attrName)
      }
    })
  }
  update(node, key, attrName) {
    let updateFn = this[attrName + "Updater"]
    updateFn && updateFn.call(this, node, this.vm[key], key)
  }
  textUpdater(node, value, key) {
    node.textContent = value;

    // 创建watcher 
    // this.vm  
    new Watcher(this.vm, key, (newValue) => {
      node.textContent = newValue;
    })
  }
  modelUpdater(node, value, key) {
    node.value = value;

    new Watcher(this.vm, key, (newValue) => {
      node.value = newValue;
    })

    node.addEventListener("input", () => {
      this.vm[key] = node.value;
    })

  }
  compileText(node) {
    let reg = /\{\{(.+)\}\}/;
    let value = node.textContent;
    if (reg.test(value)) {
      let key = RegExp.$1.trim();
      node.textContent = value.replace(reg, this.vm[key])

      // 创建watcher 
      // this.vm  
      new Watcher(this.vm, key, (newValue) => {
        node.textContent = newValue;
      })
    }
  }
  isTextNode(node) {
    return node.nodeType === 3;
  }
  isElementNode(node) {
    return node.nodeType === 1;
  }
  isDirective(attrName) {
    return attrName.startsWith("v-")
  }
}